There are many devices on the market that can be attached to a rain gutter for preventing leaves and other debris from entering the gutter. Some of these devices utilize a foam filter insert, formed from an open-cell material, that is inserted into the gutter. Such foam inserts typically have a top surface that totally closes off the top opening of the gutter so that leaves and other debris from the roof slide across the top surface without entering the gutter, while the water from the roof flows through the foam insert and into the gutter.
In U.S. Pat. No. 3,855,132 to Dugan, a filler element made of a porous foam material, and having a sloped top surface, is inserted into a gutter, so that water cascading into the gutter from a sloped roof, and carrying foreign debris from the roof, flows across the sloped top surface of the foam insert. The water flows through the foam in a vertical direction and then along the gutter in a horizontal direction to a downspout or other device for exit from the gutter. The debris is trapped on the surface of the foam filler and either dries and is blown away or is brushed off of the surface of the foam filler.
Dugan discloses embodiments wherein the foam filler occupies the entire volume defined by the gutter walls, and other embodiments where a space or open-passageway is left between the foam filler and the bottom of the gutter, so as to allow for a freer flow of liquid below the porous section of the foam filler while still achieving the debris blocking advantages of the porous nature of the foam filler. Dugan discloses that such an open-passageway configuration may be achieved by forming the filler with a precut slot on it's lower side, or by forming the filler in a size smaller than the depth of the gutter and providing spaced support along the length of the gutter to support the filler and to maintain the open passageway between it and the bottom of the gutter.
Dugan further discloses the use of a porous foam, preferably of a polyurethane variety, with a suitable foam providing a 95% void volume with an average of 10 pores per lineal inch.
U.S. Pat. No. 4,949,514 to Weller, discloses a liner for a rain gutter comprising a body of porous solid material which is installed in the gutter to form an upper barrier surface. The barrier surface has a plurality of undulations. Longitudinally extending projections at the side portions of the body function as sealing structures to seal the liner with the gutter sidewalls. The liner and gutter form a single lower longitudinally extending liquid passageway. Liquid passes through the liner to the passageway, while debris remains on the upstream side of the barrier surface. Weller also discloses that a gutter liner, in accordance with his invention, may be composed of polyurethane foam or other similar materials.
Other types of foam gutter fillers and inserts are also known which are fabricated from a polyether material.
Prior foam gutter filter inserts suffer from several significant problems, however. Some prior foam filter inserts have been shown to have inadequate fire resistance. This is particularly true for prior foam inserts made from polyether material which is not fire resistant, and is therefore readily ignited by sparks from burning leaves or fireplaces. Polyether material also has a tendency to form a hard crust on the top surface, due to exposure to sunlight and the environment. When the hard crust forms, the color of the foam insert changes from a dark color that is conducive to melting snow and ice when warmed by the sun, to a light color which does not effectively melt snow and ice when exposed to the sun. Materials used in prior foam gutter inserts also do not provide resistance to mold, and are not germicidal, factors which lead to reduced performance and unacceptably shortened operating life of the insert.
The ability of prior foam gutter inserts to pass an adequate amount of water during a heavy rain, and to allow a sufficient volume of water to flow through the gutter beneath the foam insert, to avoid overflowing the gutter, is less than adequate. In addition, the cross-sectional shapes of prior foam gutter filters are not conducive to fitting readily within standard gutter shapes, and do not provide sufficient structural stability to avoid being tipped over or deformed during a heavy rain, or where snow and ice may have built up on the edges of the roof.
What is needed, therefore, is an improved foam gutter filter for preventing leaves and debris from entering the gutter, overcoming one or more of the problems described above.